The present invention relates to an apparatus for the cooling and calibration of extruded plastic profiles with a trough which is provided downstream of a dry calibrating device and comprises a water bath through which the profile is guided, with apertures being arranged in the trough between the face walls for calibrating the profile.
An installation for the production of plastic profiles as are used for the production of windows or doors usually currently comprises the following arrangement: An extruder produces a profile of doughy consistency made of plastic granulate. One or several dry calibrating devices will cool the profile to a certain extent, so that a somewhat stable form is achieved. Dry calibration substantially consists of a steel block with an opening through which the profile is guided and with a plurality of vacuum slots in order to suck the profile under pressure against the walls of the opening. In this way the collapse of the still soft profile is prevented. Furthermore, several cooling ducts are provided. One or several wet calibrating apparatuses will ensure the final cooling and shaping of the profile. Wet calibrating apparatuses according to the so-called swirl bath principle have proven to be particularly beneficial in the past few years. In such apparatuses the trough is subdivided by calibration plates into several chambers and a turbulent flow of the cooling medium in the trough is caused by openings in the plates. A negative pressure present in the trough will press the profile against the calibration plates. This allows for a precise calibration and rapid cooling of the profile with a lower water consumption. A caterpillar pull-off will draw the profile through the upstream calibrating devices.
The technical progress of extruders and the recipes for profile extrusion has led to continuously rising demands placed on the work speed of extrusion lines. In order to meet these demands it is currently common practice to arrange several dry calibrations behind one another and, downstream of the same, to provide one or several water baths. Dry calibrations are very costly, however, so that for cost reasons a reduction in their number would be desirable.
Calibration systems can be used for slow working extrusion lines which make do with only one single dry calibration with the common length of approx. 300 mm. If in such a system the work speed is increased over a relatively moderate value, high-quality profiles can no longer be produced.